rotation referential

parent
| |
node1 motor
|
node2
|
wheel

How do I get motor rotation in the referential of the wheel (node2) without re-parenting?

you can either combine the local rotations of the nodes along the way:

var relativeRotation : Quaternion = node1Motor.localRotation * node2.localRotation * wheel.localRotation;

Or compare the worldspace rotations of the two directly:

var relativeRotation : Quaternion = wheel.rotation * Quaternion.Inverse(parent.rotation);

Thanks!

(and on the way I’m learning that quaternion multiplication is a rotation addition.)